EXTREME FEEDBACK AND THE EPOCH OF REIONIZATION: CLUES IN THE LOCAL UNIVERSE
EXTREME FEEDBACK AND THE EPOCH OF REIONIZATION: CLUES IN THE LOCAL UNIVERSE
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DOI：
10.1088/0004-637x/730/1/5
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发表时间：
2011-01
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通讯作者：
T. Heckman;S. Borthakur;R. Overzier;G. Kauffmann;A. Basu-Zych;C. Leitherer;K. Sembach;D. Martin;R. Rich;D. Schiminovich;M. Seibert
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作者：
T. Heckman;S. Borthakur;R. Overzier;G. Kauffmann;A. Basu-Zych;C. Leitherer;K. Sembach;D. Martin;R. Rich;D. Schiminovich;M. Seibert
在z>6时使宇宙再电离的来源仍然不确定。虽然可能存在能量充足的恒星形成星系，但不知道它们的电离辐射是否有足够大的部分可以逃逸到星系际介质中。在强烈的恒星形成星系中，在较低的红移下测量这种逃逸分数的尝试在很大程度上产生了上限。在本文中，我们提出了新的哈勃太空望远镜宇宙起源摄谱仪和档案远紫外光谱探测器（FUSE）远紫外光谱的样本11个莱曼破裂类似物（LBA），一个罕见的人口的本地星系，强烈类似于高z莱曼破裂星系。我们联合收割机这些数据与斯隆数字巡天光谱和斯皮策测光。我们还分析了档案FUSE观测15个典型的紫外线明亮的本地星暴。在三种情况下，我们发现了光学厚中性气体的小覆盖因子的证据。这是基于两个独立的证据：在最强的星际吸收线的核心中有一个显著的剩余强度，追踪中性气体，以及经过消隐校正的Hα与UV加远红外光度的小比率。这些天体代表了四个LBA中的三个，其中包含一个年轻的，非常紧凑的（102 pc）和高度巨大的（109 M）主导中心天体（DCO）。这三个天体与其他星系的不同之处还在于，它们显示出大量蓝移的Lyα发射，这可能与中性气体的低覆盖因子有关。在我们的样本中，所有四个具有DCO的LBA都显示出星际气体的极高速度流出，线质心蓝移约700 km s-1，最大流出速度至少达到1500 km s-1。我们表明，这些属性是一致的外流驱动的一个强大的恒星暴，是非常紧凑的。我们推测，这种极端的反馈可能需要使电离辐射从恒星形成的星系逃逸。
The source responsible for reionizing the universe at z>6 remains uncertain. While an energetically adequate population of star-forming galaxies may be in place, it is unknown whether a large enough fraction of their ionizing radiation can escape into the intergalactic medium. Attempts to measure this escape fraction in intensely star-forming galaxies at lower redshifts have largely yielded upper limits. In this paper, we present new Hubble Space Telescope Cosmic Origins Spectrograph and archival Far-Ultraviolet Spectroscopic Explorer (FUSE) far-UV spectroscopy of a sample of 11 Lyman Break Analogs (LBAs), a rare population of local galaxies that strongly resemble the high-z Lyman Break galaxies. We combine these data with Sloan Digital Sky Survey optical spectra and Spitzer photometry. We also analyze archival FUSE observations of 15 typical UV-bright local starbursts. We find evidence of small covering factors for optically thick neutral gas in three cases. This is based on two independent pieces of evidence: a significant residual intensity in the cores of the strongest interstellar absorption-lines tracing neutral gas and a small ratio of extinction-corrected Hα to UV plus far-IR luminosities. These objects represent three of the four LBAs that contain a young, very compact (∼102 pc), and highly massive (∼109 M☉) dominant central object (DCO). These three objects also differ from the other galaxies in showing a significant amount of blueshifted Lyα emission, which may be related to the low covering factor of neutral gas. All four LBAs with DCOs in our sample show extremely high velocity outflows of interstellar gas, with line centroids blueshifted by about 700 km s−1 and maximum outflow velocities reaching at least 1500 km s−1. We show that these properties are consistent with an outflow driven by a powerful starburst that is exceptionally compact. We speculate that such extreme feedback may be required to enable the escape of ionizing radiation from star-forming galaxies.